Air guns are used as a source of seismic energy for marine seismic surveys. Air guns are typically deployed in an air gun array towed by a vessel. The air gun array can include several clusters of air guns, each submersed in water and suspended from a flotation device towed by the vessel. The vessel controls the air gun array to generate seismic source signals. To generate a seismic source signal the vessel fires the air guns in the array simultaneously, and the resulting seismic signal interacts with geological features beneath the ocean floor. Reflected seismic signals are collected and analyzed to identify properties of subsurface geological formations.